The invention relates to SMT printing processes where the life (usage limits) of squeegee blades and/or a printing head can be monitored.
When using squeegee blades or a printing head for the application of solder paste, there are times when these components are removed from machines for cleaning and the like and installed in the same or different machines. As with any mechanical components, there are limits regarding the effective life of these components. Currently in SMT, there is no easy way for a user to know when a squeegee blade or print head is good or bad other than the subjective criteria, such as visual inspection.
It is well known that there are many monitoring systems for machines that can display information, such as the number of SMT boards printed, total hours of usage of the machines, etc. For example, a particular squeegee blade may have a designed life of 40,000 cycles. However, none of this information actually indicates the usage of an individual squeegee blade or print head.
With the present invention, a user can set an indicator to zero when a new squeegee blade or print head is installed. The users can then check a counter display every time a squeegee blade is put into use and when the counter display reaches a predetermined number, e.g. 40,000, the user would replace the squeegee blade or print head.
The invention takes a measurement device, a counter, and places it directly near the item of interest, the squeegee blade or print head. The counter remains on at all times thereby displaying of the usage of the squeegee blade or print head without the difficulties of looking in log books or turning on computers to see usage information.
The invention in one aspect counts and displays the number of times a squeegee blade is used based on the relative movement between opposed squeegee blade holders. Each squeegee blade holder includes an actuator and a sensor/display. The actuator of one holder communicates with the sensor of the other holder. During operation of a squeegee system when one holder moves the associated squeegee blade to and from a print stroke position the other holder moves its associated blade from and to a non-print stroke position. During the relative motion the actuator is aligned with a actuator/sensor/display.
The invention, in another aspect, counts and displays the number of times the blades of a printing head are used. An actuator is secured to the head in communication with a sensor/display also secured to the head. Each time the head moves and engages the stencil the sensor is actuated.